Soft, mushy, old spiders are difficult to study – they do not fossil as easily as bone or exoskeletons. One can therefore imagine how excited the researchers were to find 10 all-new spider fossils in a relatively unexplored area called the Jinju Formation.
The Jinju Formation is a geological area in South Korea from the Mesozoic era 252 to 66 million years ago. This new series of fossils, found in shale by researchers from the Korea Polar Research Institute and the University of Kansas, has increased the number of known spiders in the Jinju Formation from just one to eleven.
But two of these spider finds were even more exciting than the rest – their eyes still reflected light 1
"Because these spiders were kept in strange speckles on a dark rock, their rather large, big-eyed eyes were immediately apparent half-moon," said Paul Selden, a geologist at the University of Kansas.
"It became clear to me that this must have been tapestry – this is a reflective structure in an inverted eye where light is incident and then returns to retinal cells." 19659003] This structure supports night vision. The human eye has no tapetum, but many animals; For example, cat's eyes look so scary in the dark.
The researchers believe that this is the first conservation of a spider's eye metaphor in the entire fossil record.
"In spiders, those who see you with really big eyes are jumping spiders, but their eyes are normal eyes – while wolf spiders reflect their eyes in the light like cats at night," explained Selden.
"Therefore, night hunt predators tend to use this other eye: this was the first time a tapetum was found in fossils."
"It's beautiful, exceptionally well-preserved features of internal anatomy like the eye structure It really is not often that you preserve something in a fossil, "he added.
Most ancient spiders are discovered in amber because they help maintain the soft bodies of the arachnids.
However, the researchers believe that these spiders – the Koreamegops samsiki were named Jinjumegops dalingwateri – had been found in Amber, the tapetum might have been missed.
"They do not have hard shells, so they disintegrate very easily," Selden said. "It must be a very special situation where they were flushed into a body of water, they would normally swim, but here they sank, and that kept them from spoiling bacteria."
"These rocks are also with them So it may have been a catastrophic event, like an algae blooms caught and sunk in a slime, but that's a guess.
The researchers believe that these newly discovered spiders would have occupied the same niche as the jumping spider today.
"But these spiders did things differently. Their eye structure differs from jumping spiders, "explained Selden.
The search for 10 new spiders is a great asset to the variety of Cretaceous spiders – because of the lack of fossils, we just do not know much about these old spooky creepy crawlies.
But with such findings, this seems to be changing.
The research was published in the Journal of Systematic Palaeontology